--- OLD/xc/programs/xlsclients/xlsclients.c	Thu Jan  1 00:00:00 1970
+++ NEW/xc/programs/xlsclients/xlsclients.c	Thu Jan  1 00:00:00 1970
@@ -25,6 +25,7 @@
 
 #include <stdio.h>
 #include <ctype.h>
+#include <stdlib.h>
 #include <X11/Xos.h>
 #include <X11/Xlib.h>
 #include <X11/Xatom.h>